It seems like the implementation does not recognize the `union` types when enabling `withObjectType` option. I get `unhandled scalar name` error. Seems like we should add a condition to handle unions here: https://github.com/Code-Hex/graphql-codegen-typescript-validation-schema/blob/2a61ef2e07b0c19c52e752a93eeead0c0b95f0b8/src/zod/index.ts#L172